The conventional optical system for flow cytometers requires aligning the light sources in relation to the lenses to shine multiple frequencies of light on a sample simultaneously. Since the light source affects the detection of each of the detector subsystems, this alignment must be precise or the performance of the system is dramatically reduced. To achieve this precision, however, requires expensive manufacturing techniques and/or time-consuming manual alignment. Thus, there is a need in the flow cytometer field to create a new and useful optical system. This invention provides such new and useful optical system.